Several non electronic and mechanical device based fuel delivery systems have been used to supply metered quantities of fuel and air to two-stroke, fuel injected, internal combustion engines. These systems have several benefits including reduced hydrocarbon exhaust emissions, improved fuel economy, a high level of reliability, and significantly lower cost than electronically controlled fuel and air delivery systems.
Conventional carburetors are often used within the mechanical fuel and air mixture and delivery systems to deliver the engines fuel requirements in the form of a fuel and air mixture. This fuel and air mixture is supplied to an auxiliary compressor for subsequent injection into the engine. However, most conventional carburetor designs utilize a throttle valve for venturi air flow control which adversely impacts compressor efficiency at low speeds, provides increased difficulty for precise calibration of fuel delivery and requires synchronized movement with the engine air valve requiring modification of the existing engine throttle linkage. A representative fuel system describing the use of a conventional carburetor in a mechanical mixture injection system is disclosed in U.S. Pat. No. 5,271,372 and European Patent No. EP 073449 A1. Further, some conventional carburetors use more than one fuel nozzle to deliver fuel from the carburetor in order to meter fuel delivery over the wide range of engine operating conditions.